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Vaccination of parent stock with a live vaccine and revaccination with an inactivated vaccine prior to the begining of lay, was proposed as a prophylactic measure against infectious bursal disease (IBD). This vaccination schedule should ensure transfer of a protective level of maternal antibodies (MN-Abs) to progeny. For this purpose an inactivated vaccine, adjuvanted by a multiple water-in-oil-in-water emulsion (WOWE) with low content of mineral oil (30% v/v), high aqueous/oil ratio (2/1), low relative viscosity (h = 3.45) and high hydrophile-liophile balance (HLB = 9.35), was designed. Flocks of 4500 light ISA Brown SSL layers and 2400 heavy Hybro breeders were previously vaccinated with a live vaccine (Gumbokal, Pliva, Zagreb, Croatia) at the age of 10 days. The revaccination with the inactivated IBDV-WOWE vaccine was carried out prior to the laying period. Hens were i.m. revaccinated with 0.25, 0.5 or 1.0 ml vaccine/bird. Serological response was monitored during whole laying period. Eggs, collected 31 weeks after vaccination of dams, were hatched. Sera from 3- and 10-day-old hatched chickens were analysed for the presence of MN-Abs. WOWE contributes to the stability and injectability of IBDV vaccine without side effects. Serological responses (ELISA-titers) in both light and heavy breeders were directly related to the doses of the vaccine administered, but only a small variability beween the magnitude of the serological responses of flocks vaccinated with 0.25, 0.5 or 1.0 ml vaccine/bird was found. A single revaccination generated high and long-lasting humoral immunity and no additional vaccinations were required during laying period. No gross tissue damage was observed at the place of vaccine inoculation. The egg production was not influenced by the revaccination with IBDV-WOWE. The levels of specific Abs in egg yolks were at least twice higher than those in the sera of vaccinated dams. Anti-IBDV antibodies were transferred to progeny. ELISA-titer of MN-Abs in sera of 3-day-old offspring was about 2800 and declined till the 10th day of life.

Immunogenicity of an experimental vaccine against Newcastle disease (ND) was tested on chickens and turkeys under laboratory and field condition, respectively.Vaccine, prepared in form of a water-in-oil-in-water (WOW), contained detergent solubilized ND virus. 21-day-old chickens, hatched from SPF eggs, were intramuscularlly (i.m.) vaccinated with 0.2 ml vaccine containing 1, 1/25, 1/50 and 1/100 viral doses. Also, 21-day-old light laying chickens received i.m. 0.2 ml vaccine containing 1, 1/5 1/25 and 1/50 viral doses. Control groups were not vaccinated. Three weeks postvaccination, chickens were i.m. challenge infected with 106 ELD50 Herts33 strain of NDV. The vaccinal dose recommended by Eu.Ph for safetly chicken protection was detrmined according to the Spaerman-Kärber methode and it amounted to 0.5 ml vaccine with 50 PD50/dose. Turkey breeders, vaccinated with 1.0 ml vaccine at the age of 16 weeks developed a high level of NDV antibodies persisting till the end of experiment, i.e. turkey age of 50 weeks. This suggest that no additional vaccination is requred during the whole laying period.